Device and method for generating electrospray stable cone jet flow

Abstract

The electrospray is a process of crushing liquid into fine charged liquid drops with uniform particle sizes by adopting electrostatic field force. The electrospray cone jet flow means that under the specific voltage and flow range, liquid forms a cone shape at the tail end of a capillary tube, a micro jet flow is jetted out of a cone tip, and then the micro jet flow is broken into monodisperse small liquid drops with high electric quantity. The invention discloses a device and a method for generating an electrospray stable cone jet flow. A porous medium material with uniform pore diameter is used as a pressure stabilizing device, and liquid permeates into a liquid storage cavity through the porous material under the action of gravity. And the liquid can obtain stable pressure in the liquid storage cavity. And under the action of the pressure, the liquid passes through the porous material microspheres and forms a stable conical jet flow at the nozzle. The liquid flow can be changed by adjusting the height of the liquid supply level and the thickness of the porous material. When the flow is increased, the volume of the conical liquid surface is increased and is stabilized on the hemispherical nozzle; when the voltage is increased, the jet flow of the conical tip can be kept unchanged in the axial direction.

Description

Technical field:

[0001] The invention relates to the field of electrospray, and in particular to a device and method for generating an electrospray stable cone jet. Background technology:

[0002] A typical electrospray cone jet refers to squeezing liquid out of a capillary at a certain flow rate. Under the action of an external electrostatic field, a curved liquid surface is formed at the capillary outlet. The curved liquid surface becomes a cone under the action of electric field force, surface tension, gravity, viscosity and other forces. Due to the accumulation of charge, a fine jet is sprayed at the top of the liquid cone, and then breaks into fine charged droplets in different forms downstream of the jet. Compared with traditional atomization methods such as pressure atomization, centrifugal atomization, and ultrasonic atomization, electrospray can produce droplets with better monodispersity and a large amount of charge. It has important applications in biological mass spectrometry analysis, electrospray printing, electrospinning, and electroplating. In addition, by adjusting the flow rate and voltage, the motion characteristics and particle size distribution of the droplets can be effectively controlled.

[0003] The liquid supply method in the electrospray cone jet is usually provided by a syringe pump to provide pressure. When the syringe pump pushes the needle tube for injection at a certain flow rate, the outlet of the syringe needle tube is connected to a long rubber tube, and the long rubber tube is directly connected to the capillary nozzle. The rubber tube is soft and easy to twist and bend, resulting in poor infusion in the tube and liquid blockage; the pressure provided by the syringe pump is relatively large. When the viscosity of the conveying medium is relatively large, the pressure in the tube and at the tube connection is very high, which will cause the rubber tube to collapse from the needle tube outlet; the inner diameter of the nozzle used in the electrospray cone jet is very small, which is difficult to process. The tube diameter and nozzle diameter are small, and the internal pressure is high, which is easy to cause needle blockage and rubber tube collapse from the needle tube outlet; high-precision imported brand syringe pumps are expensive, occupy a large volume, and require additional layout. Based on the above shortcomings or deficiencies, the present invention proposes a hemispherical nozzle that relies on liquid gravity to penetrate a porous ceramic material and then sprays through a porous ceramic ball, which realizes the simplification of the electrospray cone jet atomization device, improves the reliability of the equipment operation, and can significantly improve the flow range of stable operation of the cone jet.

[0004] Porous ceramics are a type of material with low volume density and high porosity. They have microporous structures of similar sizes distributed inside them, and have high chemical stability. They are not easy to react chemically with liquid media, and are often used as filter materials. The permeability of liquid in porous ceramic materials mainly depends on the affinity between the solute and solvent in the liquid and the porous ceramic material. In most cases, the affinity between liquid molecules and porous ceramic materials is weak. Therefore, liquids can pass through them very effectively, and they are not easily corroded, and will not cause clogging of the holes.

[0005] The present invention designs a device capable of obtaining a stable cone jet of electrospray, the device comprising a hollow hemispherical nozzle, a hole is opened at the bottom of the nozzle and porous material microspheres are embedded. A porous ceramic material is installed inside the hollow nozzle, and the liquid penetrates into the liquid storage cavity through the porous material under the action of gravity. The liquid can obtain a stable pressure in the liquid storage cavity, and the liquid under this pressure is squeezed out through the porous material microspheres, and a cone jet is realized under the action of an external electric field. By adjusting the liquid level in the liquid supply box and the thickness of the porous material, the liquid flow Q and the shape of the liquid cone can be regulated. Summary of the invention:

[0006] The purpose of the present invention is to simplify the device for obtaining an electrospray stable cone jet. The device mainly uses porous ceramic materials. The porous medium with high porosity can effectively penetrate the liquid to achieve gravity penetration, replacing the high pressure caused by the injection pump driving the liquid supply, and avoiding the unstable operation of the equipment. The porous hemispherical shell is installed in a hollow hemispherical nozzle, and its upper end is connected to the bottom of the liquid supply box. The liquid in the liquid supply box achieves liquid penetration under the action of gravity. It seeps out from the porous hemispherical shell material and obtains a stable pressure after entering the liquid storage chamber. The liquid seeps out through the porous material microspheres and forms a stable cone jet at the nozzle under the action of an external electric field. Due to the interaction between the cone liquid surface and the hemispherical nozzle, this interaction maintains the stable state of the cone jet under high pressure, realizing the expansion of the voltage and flow range of the electrospray stable cone jet.

[0007] In order to achieve the above objectives, the technical scheme of a device and method for generating an electrospray stable cone jet designed in this paper is as follows:

[0008] A device and method for generating an electrospray stable cone jet, comprising:

[0009] The supporting unit includes an insulating bracket 9 and a pair of fixed insulating rings 8.

[0010] The liquid supply unit comprises a liquid supply box 5 with a round hole in the box cover and a liquid injection port 7.

[0011] The electrode unit includes a needle-shaped electrode 6 and a ground electrode plate 10 .

[0012] The porous material unit mainly adopts a porous medium material with high porosity, and its internal pore size is 2-50nm. The porous medium material includes a porous hemispherical shell structure 2 fixed inside a hollow nozzle 4 and a porous material microsphere 1 embedded at the nozzle outlet.

[0013] The emitter unit comprises a hollow hemispherical nozzle 4 .

[0014] Furthermore, the liquid supply box 5 has a height of 50-60 mm and a diameter of 10 mm.

[0015] Furthermore, the porous material microspheres 1 have a diameter of 0.5 to 1.0 mm.

[0016] Furthermore, the porous hemispherical shell structure 2 has a diameter of 5.0 mm and a thickness of 0.5 mm.

[0017] Furthermore, the diameter of the hemispherical nozzle 4 is 6.0 mm.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The present invention uses porous medium materials as liquid penetration structures, and installs a porous hemispherical shell structure at the bottom of the liquid supply box. The liquid in the box can penetrate into the liquid storage cavity under the action of gravity. Compared with the method of providing pressure by the injection pump to drive the liquid to achieve electrospray stable cone jet, gravity penetration can reduce the hydraulic loss caused by high pressure and improve the reliability of the device operation.

[0020] The porous medium material used in the present invention can achieve the purpose by adjusting the process means according to the required shape and pore size, which is simpler than obtaining a capillary with a small inner diameter by chemical etching.

[0021] The present invention adopts a hollow hemispherical nozzle. Under a high-voltage electric field, the interaction between the liquid cone and the hemispherical nozzle can maintain the stable state of the cone jet, thereby achieving the expansion of the voltage and flow range under the stable operation of the electrospray cone jet.

[0023] The present invention embeds porous material microspheres at the bottom of the hemispherical nozzle, and can define the maximum electric field intensity at the top of the liquid cone. Compared with ordinary nozzles, the porous material microsphere structure can stabilize the jet in the axial direction at a large flow rate. Description of the drawings:

[0024] Figure 1 A schematic structural diagram of a device and method for generating an electrospray cone jet according to the present invention is shown.

[0025] Figure 2 Shows Figure 1 Middle AA section structure diagram.

[0026] Figure 3 Shows Figure 1 Middle nozzle structure diagram.

[0027] Figure 1 1—porous material microsphere 2—porous hemispherical shell 3—pressure-stabilizing liquid storage chamber 4—hemispherical nozzle 5—insulated liquid supply box 6—needle electrode 7—liquid injection port 8—fixed insulating ring 9—insulating bracket 10—ground electrode plate

[0028] Figure 1 Medium size marking, hemispherical nozzle diameter D1 = 6.0mm porous microsphere diameter D2 = 0.5 ~ 1.0mm porous hemispherical shell thickness H1 = 0.5mm porous hemispherical shell diameter D3 = 5.0mm Specific implementation method:

[0029] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] The present invention proposes a device and method for generating a stable cone jet of electrospray, and its specific structural arrangement is as follows: Figure 1 As shown. The device is fixed by a pair of fixed insulating rings 8 on a bracket 9. The distance between the nozzle and the ground electrode plate 10 can be adjusted by a nut. A liquid injection port 7 is opened at the top of the bracket. The external device can supply liquid through the injection port 7. An insulating liquid supply box 5 is installed above the nozzle. The box cover has a round hole. A porous hemispherical shell structure 2 is installed at the bottom of the liquid supply box. The structure is located inside the hollow hemispherical nozzle. At the same time, the bottom of the hemispherical nozzle is opened and embedded with porous material microspheres 1. A grounded ground electrode plate device with adjustable height is placed under the nozzle.

[0031] At the beginning of the experiment, open the valve of the external device to inject the liquid into the liquid supply box 5 through the injection port 7. After the liquid is filled, close the valve to stop the liquid supply, and insert the needle electrode 6 into the liquid. The electrode is connected to a high-voltage electrostatic generator, which can be positive high voltage or negative high voltage. The liquid in the liquid supply box seeps out from the porous hemispherical shell structure 2 under the action of gravity, and the seeped liquid enters the liquid storage chamber 3 to obtain a stable pressure. The pressure-stabilizing liquid is squeezed out through the porous material microspheres 1 to form a conical jet under the action of an external electric field. The experiment can control the flow rate Q and the shape of the liquid cone by adjusting the liquid level height H in the liquid supply box and the thickness H1 of the porous hemispherical shell. The application of the hemispherical nozzle and porous dielectric material proposed in the present invention improves the voltage adjustment range and the stability of the cone jet under large flow rates.

Claims

1. A device and method for generating an electrospray stable cone jet, comprising a support unit, a liquid supply unit, an electrode unit, a porous material unit, and an emitter unit, characterized in that: The support unit includes an insulating bracket and a pair of fixed insulating rings, and the height of the insulating rings can be adjusted by a nut; the liquid supply unit includes an insulating liquid supply box with a water injection hole on the upper end cover and a liquid injection port, and the bottom of the liquid supply box is connected to the porous hemispherical shell structure; the electrode unit includes a charging electrode and a ground electrode plate with adjustable height, and the charging electrode can be immersed in liquid and discharge; the porous material unit includes a porous hemispherical shell structure with high porosity and porous material microspheres, the porous hemispherical shell is installed in a hollow nozzle, the upper end is connected to the bottom of the liquid supply box, and the porous material microspheres are embedded in the outlet end of the hemispherical nozzle; the emitter unit includes an internally hollow hemispherical nozzle, and the nozzle outlet has a hole and is embedded with porous material microspheres; Open the valve of the external liquid supply device, and the liquid enters the liquid supply box through the injection port. The liquid is charged by immersing the charging electrode. The charged liquid in the liquid supply box seeps out from the porous hemispherical shell under the action of gravity and enters the liquid storage cavity to obtain a stable pressure. The pressure-stabilizing liquid is squeezed out from the porous material microspheres to form a stable cone jet under the action of the electric field. The flow rate Q and the shape of the liquid cone can be controlled by adjusting the liquid level H in the liquid supply box and the thickness of the porous hemispherical shell.

2. The device and method for generating an electrospray stable cone jet according to claim 1, characterized in that The porous hemispherical shell has a diameter of 5.0 mm and a thickness of 0.5 mm. The porous medium material with high porosity can effectively penetrate the liquid to achieve gravity penetration, replacing the high pressure brought by the injection pump to drive the liquid, avoiding unstable operation of the equipment. By adjusting the liquid height H in the liquid supply box and the thickness of the porous medium material, the flow rate Q and the cone jet morphology can be regulated.

3. The device and method for generating a stable cone jet of electrospray according to claim 1, characterized in that The liquid supply box is a cylinder with a hole at the upper end, and its volume is in milliliters and can be adjusted between 1.0 mL and 10.0 mL. Liquid can be injected into the liquid supply box through the hole, and the charging electrode can be inserted into the liquid through the hole to charge the liquid.

4. The device and method for generating a stable cone jet of electrospray according to claim 1, characterized in that The hemispherical nozzle can generate a stable cone jet, thereby achieving an expansion of the voltage and flow range under stable operation of the electrospray cone jet.

5. The device and method for generating a stable cone jet of electrospray according to claim 1, characterized in that The porous material microspheres are embedded in the opening end of the hemispherical nozzle and have a diameter of 0.5 mm to 1.0 mm, which can obtain the maximum electric field intensity at the top of the liquid cone and maintain the stability of the cone jet under a large flow rate Q.

6. The device and method for generating an electrospray stable cone jet according to claim 5, characterized in that The porous material microspheres can be replaced by porous micro cylinders, the cylinder diameter is 0.5 mm to 1.0 mm, and the length is 1.0 mm, which can achieve the expansion of the conical jet flow range.

7. The device and method for generating a stable cone jet of electrospray according to claim 1, characterized in that The height of the ground electrode plate can be adjusted by a nut, which can effectively adjust the electric field strength between the charging electrode and the ground electrode, and realize the regulation of the cone jet shape.

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